In most dental, in particular endodontic, procedures the achievement of a good seal between the tooth and the filling composition is very much essential in order to prevent bacterial recontamination of the root canal and ensure long-term clinical success. The presence of marginal gaps between the interfaces of retrofilling compositions and root dentin are sites of possible micro leakage and penetration of microorganisms and their toxins which disables the total integrity of the dental repair compounds.
The most common dental filling material that used is Gutta-Percha, which is a natural resin and a thermoplastic rubber. However, the non-adhesive character of Gutta-Percha and the irregularities on the internal surface of the root canal makes it difficult to seal off the root canal completely. In order to overcome this limitation, sealants are used along with Gutta-Percha. Numerous sealants have been known in the art, for example, epoxy resins, calcium hydroxide, and zinc oxide eugenol-based sealers. During the root canal filling process, such materials are first applied to the Gutta-Percha, which is then inserted into the root canal. Alternatively, they may be inserted using a file or reamer applicator, so that the spaces between the Gutta-Percha points and the root canal walls can be sealed. However, controlling the exact amount of the sealant and/or filling material within the root canal to avoid overextension or overfilling has long been a challenge for endodontists. For example, in case of overflow of root canal sealant from the apical foramen into the periradicular tissue during a root canal filling process, the excess material should be desirably tolerated by the surrounding tissue.
One of the drawbacks of conventional sealants is that they tend to be hydrophobic, making them incompatible with moist tissues within the root canal. Thus the hydrophilic nature of the root canal environment inhibits adequate penetration, complete wetting, and efficient adhesion of the hydrophobic sealant to the root canal walls. As a result, a poor seal is made between the Gutta-Percha and the root canal walls leading to re-entrance of microorganisms into the canal. In addition, overfilled Gutta-Percha and/or conventional sealant materials irritate the periapical soft tissues and do not stimulate healing and hard tissue formation. Moreover, and most importantly, Gutta-Percha and conventional sealants degrade during long-term exposure to fluids present in the oral cavity.
Mineral trioxide aggregate (MTA) (ProRoot MTA, Dentsply) is one commonly used dental cements that consists of at consists of 75% Portland cement, 20% bismuth oxide, and 5% gypsum by weight which is used as a root-filling material. Some difficulties are reported by clinicians when using MTA including poor handling characteristic and lengthy setting time.
White Mineral Trioxide Aggregate (WMTA) is another one of the commonly used dental cements, which is also used as a root-end filling material. While WMTA has many advantages including biocompatibility, good sealing ability, and antibacterial properties, it suffers from low pH resistance, which affects the microhardness, and long setting time. Conventional materials like calcium aluminates and bismuth oxide result in discoloration of the tooth. Bismuth oxide in the presence of sodium hypochlorite which is used as the irrigation solution results in discoloration of tooth, see Marina Angélica Marciano et al., Clin Oral Investig. 2015 December; 19(9):2201-9.
Therefore, in the light of the above discussion, there remains a need for a multi-purpose dental composition to be used in root canal treatments, root-end filling procedures, and pulp capping, which nullifies the drawbacks of aforementioned dental materials used for the same.